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  • Articles: DFG German National Licenses  (4)
  • methane activation  (2)
  • Computational Chemistry and Molecular Modeling  (1)
  • dioxygen species and mono-oxygen species  (1)
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  • Articles: DFG German National Licenses  (4)
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Years
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 40 (1996), S. 101-104 
    ISSN: 1572-879X
    Keywords: ethane oxidative dehydrogenation ; O2 activation ; SmOF ; dioxygen species and mono-oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The activation of O2 over SmOF was studied by in situ laser Raman spectrometry and temperature programmed desorption (TPD). When the hydrogen- and helium-treated (1 h for each gas at 973 K) SmOF sample was cooled to 303 K in oxygen, Raman bands which correspond to the existence of O 2 2− , O 2 n− (2 〉n 〉 1), O 2 − and O 2 δ- (1 〉δ 〉 0) species were observed. From 303 to 973 K, there was no O2 desorption but the Raman bands observed at 303 K reduced in intensity and vanished completely at 973 K, even though the sample was under an atmosphere of oxygen. We suggest that as the sample temperature increased, dioxygen species were converted to mono-oxygen species such as O− which were undetectable by Raman spectrometry. O2 desorption occurred above 973 K, giving a TPD-peak at 1095 K. When C2 H6 was pulsed over the sample pretreated with oxygen and helium at 973 K, C2H4 selectivity was 91.8%. We conclude that the mono-oxygen species is responsible for the oxidative dehydrogenation of ethane to ethene.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 36 (1996), S. 159-163 
    ISSN: 1572-879X
    Keywords: methane activation ; Cu/La2O3 and Ni/La2O3 catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Methane was pulsed over pure CuO and NiO as well as Cu/La2O3 and Ni/La2O3 catalysts at 600° C. Results indicate that the mechanisms for methane activation over copper and nickel are quite different. Over CuO, methane is converted to CO2 and H2O, most likely via the combustion mechanism; whereas metallic copper does not activate methane. Over NiO in the presence of metallic nickel sites, methane activation follows the pyrolysis mechanism to give CO, CO2, H2 and H2O. Similar results were obtained over the Cu/La2O3 and Ni/La2O3 catalysts. XRD investigations indicate that copper and nickel existed as CuLa2O4 and LaNiO3 respectively in the La2O3-supported catalysts. The effect of La2O3 on the activation of methane is discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 27 (1994), S. 199-206 
    ISSN: 1572-879X
    Keywords: pulse reaction ; NiO/Al2O3 catalysts ; methane activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pulse studies of the interaction of CH4 and NiO/Al2O3 catalysts at 500°C indicate that CH4 adsorption on reduced nickel sites is a key step for CH4 oxidative conversion. On an oxygen-rich surface, CH4 conversion is low and the selectivity of CO2 is higher than that of CO. With the consumption of surface oxygen, CO selectivity increases while the CO2 selectivity falls. The conversion of CH4 is small at 500°C when a pulse of CH4/O2 (CH4∶O2=2∶1) is introduced to the partially reduced catalyst, indicating that CH4 and O2 adsorption are competitive steps and the adsorption of O2 is more favorable than CH4 adsorption
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 21 (1982), S. 179-190 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present summary results of a bound-state perturbation theory for a one-space and one-time dimension nonrelativistic spinless (Schrödinger) particle, a relativistic spinless (Klein-Gordon) particle, and a relativistic spin-half (Dirac) particle in central fields due to scalar or fourth-component vector-type interactions for an arbitrary bound state. This is accomplished by the reduction of the wave equations to Ricatti form. This enables a decoupling between the pair of coupled first order differential equations on the large and small component Dirac wave functions or a decoupling of the second order differential equation in the Schrödinger or Klein-Gordon equations. All corrections to the energies and wave functions, including corrections to the positions of the nodes in excited states, are expressed in quadratures in a hierarchial scheme, without the use of either the Green's function or the sum over intermediate states. For the ground states of a Schrödinger particle, it is possible to extend this technique to multidimension in the case where the perturbation is due to noncentral fields, for example, in the problem of a nonrelativistic hydrogen atom in a linear combination of multiple fields.
    Type of Medium: Electronic Resource
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